The invention relates to a front-hood arrangement wherein a front hood of a vehicle is coupled to the frame of the vehicle via at least one multiple-joint hinge, which front hood furthermore can be locked by means of at least one hood lock. The invention also relates to a hood lock for locking a front hood to a body of a vehicle.
By now, numerous safety devices, such as airbags and the like, for passengers in automobiles are known from practical applications. By contrast, protective measures for pedestrians who are hit by the front end of a passenger automobile have to date scarcely been proposed or implemented in practice. Accidents involving pedestrians which take place at speeds of up to 60 km/h have proven particularly problematical, since, if the pedestrian is hit head-on, his head often strikes the engine hood of the passenger automobile, and the pedestrian dies from his injuries. The seriousness of the injury results from the fact that although the front or engine hood, which is usually formed from thin metal sheet, would tend to bend, it then strikes parts which are arranged beneath the engine hood and in practice cannot be deformed or can only be deformed with difficulty, such as the engine block, the suspension-leg carrier, the air filter, the valve cover or the frame side and cross members of the vehicle. It would be desirable if the consequences of an impact in particular of the head of a pedestrian could be made less severe. By contrast, at speeds of over 60 km/h, the pedestrian, after he has been hit, is thrown over the vehicle.
DE-C-29 22 893 proposes that the engine hood and the wing, in the region of the joint formed between these two parts, be supported, by means of energy-absorbing U-sections which run along the two parts, on body components, and in the event of a collision these U-sections convert the impact into deformation energy. A first drawback of this arrangement is that considerable forces have to act on the sections in order to bend them. Moreover, these otherwise useless U-sections are expensive to procure and difficult to fit.
DE-A-27 37 876 describes an impact protection device which uses a prestressed pivot flap to displace a mesh-like absorption element out of an at-rest position, in which the mesh rests substantially on the front hood, into an absorbing position, which runs substantially in front of the windshield of the automobile. This device is used more to protect the windshield than the pedestrian from an excessively hard impact on the front hood. Moreover, any contact with the sensor which triggers the pivoting movement and is integrated in the front bumper can cause the mesh to be triggered, with the result that a whole range of situations arise in which the mesh completely blinds the driver.
DE-A-28 41 315 describes a safety device in which, in reaction to a signal from a sensor arranged at the front of a vehicle, to detect a collision with a pedestrian, the front hood is displaced out of an at-rest position into an impact position, which is raised with respect to the at-rest position, by a piston-cylinder unit, the displacement being effected by an energy store. During the raising operation, the front hood is pivoted about a horizontal pivot pin which is arranged at the front of the vehicle.
DE-A-197 10 417 describes an arrangement for lifting the front hood in which pivoting about a horizontal pivot pin arranged at the front of the vehicle is triggered by the same pneumatic spring which also assists with the raising of the front hood which is coupled to the other end.
DE-A-197 21 565 describes a safety device on motor vehicles for raising the front hood in which the raising of the front hood takes place in a speed-dependent manner by means of a mechanism which is integral with the hood lock. For this purpose, either the unlocking of the lock which is acted on by a compression spring, which for safety reasons is normally triggered from the driver's compartment, is triggered by a sensor which is triggered by an impact, or alternatively, particularly at relatively high speeds, a piston-cylinder unit which is integrated in the catch bolt of the hood lock is expanded by a propelling charge. A first drawback of this arrangement is that the force required to close the front hood must not exceed a defined threshold, in order to allow the driver to close the front hood with ease. Since the forces which strike in the event of an accident involving a person are considerable, the front hood is pressed down rapidly, and the known injuries occur, in particular in the region of the head. Providing a propelling charge in order to expand a piston-cylinder unit also causes problems, since the service life of this charge, in particular in a relatively unprotected arrangement, is limited, and the charge is difficult to exchange. Moreover, there is a risk of the compression spring and the piston-cylinder unit being triggered simultaneously, with the result that the opening of the front bonnet would become so great that the airstream would bring the hood into contact with the windshield, thus preventing the driver from being able to see.
DE-A-27 11 338 describes a device for damping the impact of a pedestrian, in which an airbag is arranged in the region of the cowl, the filling of which airbag is triggered by a sensor signal. In this case, the airbag may be arranged in such a way that, at the same time, it raises a part of the front hood; to do this it overcomes a spring force which preloads two links, which are connected to one another via a rotation point and one of which is arranged rotatably on the front hood and the other of which is arranged rotatably on a fixed part of the motor vehicle, into an angled position. Furthermore, it is proposed to arrange resilient profiled bodies in strip form in the manner of a seal between hood and side parts, in order in this way to provide further protection in the event of an impact.
DE-A-27 11 339 describes a front hood which is coupled at the front side and in which the coupling is designed to be resilient, in such a manner that it allows a horizontal displacement of the front hood through the impact of a pedestrian, the front hood which is displaced toward the rear being connected at the rear side to one end of a rigid locking element, the other end of which, in the event of displacement of the front hood, is displaced upward and toward the rear in a guide curve in such a manner that the front hood executes an upward movement. This lifting only takes place if horizontal displacement of the front hood has actually occurred, which is not always the case, for example, in the event of impacts of children.
EP-A-0 509 690 describes a front hood, which at its front side is coupled to the vehicle structure in such a manner that, as a result of an impact, the front hood is displaced toward the rear, the closure or pivot means arranged at the rear side, as a result of a movement of the front hood toward the rear, triggering an upward pivoting movement of the front hood, so that the deformation travel of the hood is increased in the event of the impact of a pedestrian. The pivoting movement is guided, for example, by a four-joint hinge, which is otherwise used to pivot the front hood when it is desired to release access to the engine and other parts. In this case too, the front hood is only lifted in the event of a very substantial displacement of the front hood, while a weak impact does not displace the front hood toward the rear and therefore upward.
DE-A-197 12 961 describes the arrangement of a front hood on a vehicle in which a hinge is arranged on a hinge mount, which hinge mount, in the event of a collision with a pedestrian, is pivoted upward in order to raise the front hood. A problem of this arrangement is that the hood lock for the front hood defines a pivot axis which does not allow optional displacement of the hinge mount, and consequently the hinge mount described is, for example, blocked.
DE-A-197 06 878 describes an engine hood which, in the event of a head-on collision, is intended to substantially cover the area of the windshield in the manner of a protective plate, in order to protect passengers in the vehicle from objects penetrating into the passenger compartment. For this purpose, the front hood is held by means of a bolt, which is designed with a desired breaking point, in the hood lock, is mounted on the body by means of a hinge arrangement in the form of a U-bow and is prestressed to erect the front hood in the event of a head-on collision by means of a stressing arrangement. First of all, it should be pointed out that the proposed solution is in no way suitable for combating the impact of a pedestrian, since the impact would have to apply at least sufficient force to shear off the bolt in the hood lock, yet a weak bolt of this type would not be suitable for everyday use. Moreover, the front hood is raised too slowly, and because of the displacement of the front-side end the engine compartment, together with its components which are dangerous to pedestrians, is in fact exposed, while the passengers in the vehicle, who are sufficiently protected by a laminated glass windshield, are provided with additional security.
EP-B-0 630 801 describes a front-hood arrangement in which the front hood is mounted by means of link arrangements arranged in the front region of the body and is held by a retaining device arranged in the region of the cowl; in this arrangement, the joint assemblies, which are designed in a similar manner to a four-joint mechanism, are designed in such a manner that on the one hand they can be pivoted about an axis which runs in the front region of the vehicle, in order for the front hood to be opened by tilting, and secondly, when a force acting on the front edge of the front hood is applied, they can be moved upward by the four-joint mechanism. For this purpose, a front hood which is likewise to be displaced upward is provided in the region of the retaining devices, this being achieved, for example, by the fact that a suspendable retaining arm, after a shear-off bolt has been sheared off from the holding means connected to the front hood, allows a further pivoting movement substantially in the upward direction. The axis in which the retaining bolt is held remains unchanged. Alternatively, it is proposed for the axis to be displaced along a guide rail which, however, primarily involves raising of the front hood.
EP-B-0 644 104 describes a front-hood arrangement in which the front hood can be pivoted upward by means of its rear edge about a hinge or joint provided in the region of its front edge, in order to provide access to the engine compartment, the hinge which guides the front hood at the front not being secured to the body, but rather to a front part of the vehicle which comprises, for example, the radiator area, and which is pivotably connected, via a further hinge, to a front cross member of the body, so that in the event of a pedestrian striking the radiator part or the front hood both parts are displaced toward the rear. For this purpose, a guide path, in which a roller of the lock can be displaced substantially in such a manner that the front hood is shifted upward, is provided in the region of the lock, which is provided at the rear.
Overall, as yet no solution has been proposed which proposes an inexpensive arrangement, which can be readily restored after use and which is so well developed that it could be used in mass-produced vehicles.